是否可以使用 Swashbuckle 为 oneof 属性生成引用模式？

Question

默认情况下， Swashbuckle为oneof属性（universeCategory）生成一个内联模式，如下所示。

"Universe":{
  "type":"object",
  "properties":{
    "universeCategory":{
      "oneOf":[
        {
          "$ref":"#/components/schemas/FullUniverse"
        },
        {
          "$ref":"#/components/schemas/HalfUniverse"
        }
      ],
      "discriminator":{
        "propertyName":"source",
        "mapping":{
          "FullUniverse":"#/components/schemas/FullUniverse",
          "HalfUniverse":"#/components/schemas/HalfUniverse"
        }
      }
    }
  }
}

是否可以通过将一些配置传递给Swashbuckle来生成如下所示的引用模式？

"Universe":{
  "type":"object",
  "properties":{
    "universe":{
      "$ref":"#/components/schemas/UniverseCategory"
    }
  },
  "additionalProperties":false
},
"UniverseCategory":{
  "oneOf":[
    {
      "$ref":"#/components/schemas/HalfUniverse"
    },
    {
      "$ref":"#/components/schemas/FullUniverse"
    }
  ],
  "discriminator":{
    "propertyName":"source",
    "mapping":{
      "HalfUniverse":"#/components/schemas/HalfUniverse",
      "FullUniverse":"#/components/schemas/FullUniverse"
    }
  }
}

Open API 生成器等工具目前仅支持上述格式。 因此，任何为oneof属性生成引用模式的解决方法都值得赞赏。

Answer 1

我们可以添加一个自定义过滤器来将 oneof 模式的生成作为单独的模式来处理，并且可以添加对生成的新模式的引用。

public class HandleOneOfPropertiesFilter : ISchemaFilter
{
    public void Apply(OpenApiSchema schema, SchemaFilterContext context)
    {
        if (schema?.Properties == null || context.Type == null)
        {
            return;
        }
        
        var propertiesWithOneOfHandling = context.Type.GetProperties()
            .Where(t => t.GetCustomAttributes().Any(c => c.GetType() == typeof(HandleOneOfPropertiesAttribute)));

        foreach (var selectedProps in propertiesWithOneOfHandling)
        {

            foreach (var props in schema.Properties)
            {
                if (selectedProps.Name.Equals(props.Key, StringComparison.InvariantCultureIgnoreCase))
                {
                    var oneOfProperty = (HandleOneOfPropertiesAttribute)context.Type.GetProperty(selectedProps.Name)
                        .GetCustomAttribute(typeof(HandleOneOfPropertiesAttribute));
                    
                    var name = oneOfProperty.Prefix + selectedProps.Name;

                    if (props.Value.Type == "array")
                    {
                        // Handling array type differently
                        context.SchemaRepository.Schemas.Add(name, props.Value.Items);
                        
                        var newSchema = new OpenApiSchema();
                        newSchema.Type = "array";
                        newSchema.Items  = new OpenApiSchema
                        {
                            Reference = new OpenApiReference
                            {
                                Id = name,
                                Type = ReferenceType.Schema
                            }
                        };
                        context.SchemaRepository.Schemas.Add(name + "Array", newSchema);
                        props.Value.Reference = new OpenApiReference
                        {
                            Id = name + "Array",
                            Type = ReferenceType.Schema
                        };
                    }
                    else
                    {
                        context.SchemaRepository.Schemas.Add(name, props.Value);    
                        props.Value.Reference = new OpenApiReference
                        {
                            Id = name,
                            Type = ReferenceType.Schema
                        };
                    }
                }
            }
        }
    }
}

然后我们需要定义一个属性来确定我们需要在哪些属性上处理生成，让我们创建属性

public class HandleOneOfPropertiesAttribute : Attribute
{
    public HandleOneOfPropertiesAttribute(string prefix)
    {
        Prefix = prefix;
    }
    
    public string Prefix { get; }
}

然后我们需要将此属性用于 model 的 oneof 类型的属性。 在下面的代码片段中，我使用了“OneOfProp”前缀，因此生成的新模式将具有此前缀

public class ModelClass
{
   
    [HandleOneOfProperties("OneOfProp")]
    public Universe property1 { get; set; }


    [HandleOneOfProperties("OneOfProp")]
    public Galaxy property2 { get; set; }
}

最后在服务中注册这个过滤器

services.AddSwaggerGen(c =>
 {
   c.SchemaFilter<HandleOneOfPropertiesFilter>();
 });